Customary self-supporting vehicle bodies for passenger vehicles, including the associated supporting structure, are manufactured from sheet-metal parts. The bearer members which have hollow profiles are formed by welding together two deep-drawn metal sheets or stampings. The bearer joints which form the connection of two bearers are typically formed by overlapping adjoining bearer ends and joining them at the points of contact with a weld seam or several spot welds.
The steel sheets used to construct such self-supporting vehicle bodyworks are typically shaped in a deep drawing process. While the dies used for shaping the steel sheets are relatively expensive, they do provide a cost-favorable solution for mass production since they permit large production runs. However, in view of the high investment costs for tooling, the aforesaid process is very cost-intensive for smaller production runs.
A more cost-favorable solution for small production runs is known, for example, from European Patent document EP 0 146 716. This document discloses a vehicle body for a passenger car comprising a bearing structure assembled from a plurality of hollow section frame members which are joined together by nodes or junction elements. The hollow section frame members are formed as extruded light-alloy (aluminum) sections and the junction elements are formed as light- alloy castings. In addition to being a more cost-favorable solution for small production runs, a light-alloy bodywork of the type disclosed in EP 0 146 716 weighs less and is more resistant to corrosion than a sheet metal bodywork.
In the case of such a light-alloy bodywork, the front end longitudinal bearer assembly is assembled from bearer members of different profiles. The bearer members are joined by inserting an end of a first bearer member within a receiving end of a second bearer member or by placing them against one another in positive engagement after which they are then fixed in place by welding. A longitudinal bearer member joint is subject to very high loads, particularly during frontal impact. Accordingly, this joint is designed with suitably large dimensions to ensure adequate rigidity and strength.
German patent document DE 38 11 427 discloses a contact joint for connecting two axially aligned hollow section longitudinal bearer members, each having the same polygonal cross-sectional profile, wherein the adjoining end of one bearer member is notched for fitted insertion within the receiving adjoining end of the other bearer member. Adhesive is applied to the notched surfaces prior to insertion. A disadvantage here, however, is that only longitudinal bearer members of the same cross-sectional profile may be joined by such a technique.
French patent document FR 775 182 discloses a sheet metal clam shell junction element for connecting the ends of four tubular longitudinal members at right angles to one another. The clam shell junction element comprises a top and bottom half shell portions. When assembled, the top and bottom half shell portions fully enclose the adjoining bearer member ends and are welded together at mating edges thereof. The resulting weld seam is disposed in a horizontal plane at the approximate middle of the assembly and therefore lies disadvantageously in a zone subject to very high loads.